A typical computer system includes at least a microprocessor and some form of memory. The microprocessor has, among other components, arithmetic, logic, and control circuitry that interpret and execute instructions necessary for the operation and use of the computer system. FIG. 1 shows a typical computer circuit board (10) having a microprocessor (12), memory (14), integrated circuits (16) that have various functionalities, and communication paths (18), i.e., buses and wires, that are necessary for the transfer of data among the aforementioned components on the circuit board (10).
Integrated circuits (16) and microprocessors (12), such as the ones shown in FIG. 1, are electrically connected, i.e., xe2x80x9cmounted,xe2x80x9d to the circuit board (10) via chip packages. A chip package houses semiconductor devices in strong, thermally stable, hermetically-sealed environments that provide a semiconductor device, e.g., an integrated circuit, with electronic connectivity to circuitry external to the semiconductor device.
FIG. 2 shows a typical chip package assembly. In FIG. 2, an integrated circuit (20) is mounted onto a chip package (22), where an active side (24) of the integrated circuit (20) is electrically interfaced to the chip package (22). Specifically, the integrated circuit (20) has bumps (26) on bond pads (also known in the art as xe2x80x9clanding padsxe2x80x9d) (not shown) formed on the active side (24) of the integrated circuit (20), where the bumps (26) are used as electrical and mechanical connectors. The integrated circuit (20) is inverted and bonded to the chip package (22) by means of the bumps (26). Various materials, such as conductive polymers and metals (referred to as xe2x80x9csolder bumpsxe2x80x9d), are commonly used to form the bumps (26) on the integrated circuit (20).
As discussed above with reference to FIG. 2, the bumps (26) on the integrated circuit (20) serve as electrical pathways between components within the integrated circuit (20) and the chip package (22). Within the integrated circuit (20) itself, an arrangement of conductive pathways and metal layers form a means by which components in the integrated circuit (20) operatively connect to the bumps (26) located on an exterior region of the integrated circuit (20). To this end, FIG. 3a shows a side view of the integrated circuit (20). The integrated circuit (20) has several metal layers, M1-M8, surrounded by some dielectric material (28), e.g., silicon dioxide. The metal layers, M1-M8, are connected to each other by conductive pathways (30) known as xe2x80x9cvias.xe2x80x9d Vias (30) are essentially holes within the dielectric material (28) that have been doped with metal ions. Further, those skilled in the art will understand that although FIG. 2 shows only eight metal layers and a particular amount of vias, integrated circuits may have any number of metal layers and/or vias.
Circuitry (not shown) embedded on a substrate of the integrated circuit (20) transmit and receive signals and power via the metal layers, M1-M8, and the vias (30). Signals that need to be transmitted/received to/from components external to the integrated circuit (20) are propagated through the metal layers, M1-M8, and vias (30) to the top metal layer, M8. The top metal layer (also referred to and known as xe2x80x9cpower gridxe2x80x9d), M8, then transmits/receives signals and power to/from the bumps (26) located on the active side (24) of the integrated circuit (20). With respect to the power and energy needed by the integrated circuit (20), power is delivered to the integrated circuit (20) from external sources through the bumps (26) and metal layers, M1-M8. The top metal layer, M8, on the integrated circuit (20) acts as an interface between the integrated circuit (20) and the external sources/signals of power.
FIG. 3b shows a top view of the integrated circuit (20) shown in FIG. 3a. The top metal layer, M8, as shown in FIG. 3b, has a number of parallel regions, otherwise known as xe2x80x9cmetal bars.xe2x80x9d These metal bars alternate between bars connected to VDD and regions connected to Vss. Such a configuration helps reduce electromagnetic interference. The top metal layer, M8, is configured such that it is orthogonal with the metal layer below, M7, as shown in FIG. 3b. Further, bumps (26) on the top metal layer, M8, are arranged in a non-uniform fashion with some areas of the top metal layer, M8, having larger numbers of bumps (26) than other areas.
According to one aspect of the present invention, a method for designing an integrated circuit having a top metal layer that has a first metal bar and a second metal bar comprises defining a desired angle, where the desired angle represents an angle formed between a line from a reference bump to a first bump and a line from the reference bump to a second bump, where the first and second bumps reside on the first metal bar, and where the reference bump resides on the second metal bar; and using the desired angle to position the first metal bar, the first bump, and the second bump on the integrated circuit.
According to another aspect, a method for designing an integrated circuit having a top metal layer that has a first metal bar and a second metal bar comprises defining a desired angle, where the desired angle represents an angle formed between a line from a reference bump to a first bump and a line from the reference bump to a second bump, where the first and second bumps reside on the first metal bar, and wherein the reference bump resides on the second metal bar; and using the desired angle to position the first metal bar and the second metal bar on the integrated circuit.
According to another aspect, a computer system comprises a processor, a memory, and instructions, residing in the memory and executable on the processor, for determining a value of an angle between a line from a reference bump to a first bump and a line from the reference bump to a second bump.
According to another aspect, a computer-readable medium having instructions therein executable by processing, where the instructions are for: inputting a desired metal layer property; and determining a value of an angle between a line from a reference bump to a first bump and a line from the reference bump to a second bump based on the desired metal layer property, where the reference bump resides on a first metal bar, and where the first and second bumps reside on a second metal bar.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.